{"abstract":"A regenerating task completed early is rescheduled from its old due date.","category":"Calendar recurrence rules","checks":7,"contract":"A recurring task first due on first_due repeats every interval_days. Completions are processed in chronological order. mode \"regenerate\": the next due date is completion + interval. mode \"schedule\": completing advances to the next scheduled due date, skipping every scheduled date on or before the completion date. If the resulting due date passes until (inclusive bound, may be None), the task has no next due date (None).","contract_signature":"first_due, interval_days, mode, completions, until","evaluation_group":"w2-calendar-recurrence-rules-regenerating-task-due","failed_approach":"The partial repair `max(cd, due) + step` still uses the old due date when the task is completed early.","family":"w2-calendar-recurrence-rules-regenerating-task-due-regenerate-base","id":"FA-77326","implementations":{"attempt":{"sha256":"58d631dafbcd0310b0d82c5c2db59031eb0e941881d7ecea4eea54c7a33cfc8e","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport datetime as dt\nimport calendar\nN = 1\nobservations = []\ndef solve(first_due, interval_days, mode, completions, until):\n    due = dt.date.fromisoformat(first_due)\n    end = dt.date.fromisoformat(until) if until else None\n    step = dt.timedelta(days=interval_days)\n    for c in sorted(completions):\n        cd = dt.date.fromisoformat(c)\n        if mode == 'regenerate':\n            due = max(cd, due) + step\n        else:\n            due = due + step\n            while due <= cd:\n                due += step\n        if end is not None and due > end:\n            return None\n    return due.isoformat()\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: late completion on next due',\n   ['2024-01-01', 7, 'schedule', ['2024-01-08'], None],\n   '2024-01-15'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12'),\n  ('late completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-20'], None], '2024-01-27'),\n  ('out of order schedule', ['2024-01-01', 7, 'schedule', ['2024-01-20', '2024-01-02'], None], '2024-01-22'),\n  ('multiple missed schedule', ['2024-01-01', 3, 'schedule', ['2024-01-11'], None], '2024-01-13'),\n  ('until exact', ['2024-01-01', 7, 'schedule', ['2024-01-01'], '2024-01-08'], '2024-01-08'),\n  ('until passed', ['2024-01-01', 7, 'schedule', ['2024-01-01', '2024-01-08'], '2024-01-10'], None)],\n [('late completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-20'], None], '2024-01-27'),\n  ('out of order schedule', ['2024-01-01', 7, 'schedule', ['2024-01-20', '2024-01-02'], None], '2024-01-22'),\n  ('multiple missed schedule', ['2024-01-01', 3, 'schedule', ['2024-01-11'], None], '2024-01-13'),\n  ('until exact', ['2024-01-01', 7, 'schedule', ['2024-01-01'], '2024-01-08'], '2024-01-08'),\n  ('until passed', ['2024-01-01', 7, 'schedule', ['2024-01-01', '2024-01-08'], '2024-01-10'], None),\n  ('until regenerate', ['2024-02-01', 10, 'regenerate', ['2024-02-05'], '2024-02-15'], '2024-02-15'),\n  ('no completions', ['2024-02-01', 10, 'schedule', [], None], '2024-02-01'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12')],\n [('multiple missed schedule', ['2024-01-01', 3, 'schedule', ['2024-01-11'], None], '2024-01-13'),\n  ('until exact', ['2024-01-01', 7, 'schedule', ['2024-01-01'], '2024-01-08'], '2024-01-08'),\n  ('until passed', ['2024-01-01', 7, 'schedule', ['2024-01-01', '2024-01-08'], '2024-01-10'], None),\n  ('until regenerate', ['2024-02-01', 10, 'regenerate', ['2024-02-05'], '2024-02-15'], '2024-02-15'),\n  ('no completions', ['2024-02-01', 10, 'schedule', [], None], '2024-02-01'),\n  ('completion after until but due inside',\n   ['2024-03-01', 30, 'schedule', ['2024-03-05'], '2024-03-31'],\n   '2024-03-31'),\n  ('two schedule completions',\n   ['2024-04-01', 14, 'schedule', ['2024-03-30', '2024-04-10'], None],\n   '2024-04-29'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12')],\n [('until passed', ['2024-01-01', 7, 'schedule', ['2024-01-01', '2024-01-08'], '2024-01-10'], None),\n  ('until regenerate', ['2024-02-01', 10, 'regenerate', ['2024-02-05'], '2024-02-15'], '2024-02-15'),\n  ('no completions', ['2024-02-01', 10, 'schedule', [], None], '2024-02-01'),\n  ('completion after until but due inside',\n   ['2024-03-01', 30, 'schedule', ['2024-03-05'], '2024-03-31'],\n   '2024-03-31'),\n  ('two schedule completions',\n   ['2024-04-01', 14, 'schedule', ['2024-03-30', '2024-04-10'], None],\n   '2024-04-29'),\n  ('out of order regenerate',\n   ['2024-04-01', 5, 'regenerate', ['2024-04-09', '2024-04-02'], None],\n   '2024-04-14'),\n  ('regression: late completion on next due',\n   ['2024-01-01', 7, 'schedule', ['2024-01-08'], None],\n   '2024-01-15'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12')],\n [('no completions', ['2024-02-01', 10, 'schedule', [], None], '2024-02-01'),\n  ('completion after until but due inside',\n   ['2024-03-01', 30, 'schedule', ['2024-03-05'], '2024-03-31'],\n   '2024-03-31'),\n  ('two schedule completions',\n   ['2024-04-01', 14, 'schedule', ['2024-03-30', '2024-04-10'], None],\n   '2024-04-29'),\n  ('out of order regenerate',\n   ['2024-04-01', 5, 'regenerate', ['2024-04-09', '2024-04-02'], None],\n   '2024-04-14'),\n  ('regression: late completion on next due',\n   ['2024-01-01', 7, 'schedule', ['2024-01-08'], None],\n   '2024-01-15'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12'),\n  ('late completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-20'], None], '2024-01-27')]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"705af698a6e8446b5882e15521ff4f927059bd4801636f853d4e42497a75b92a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport datetime as dt\nimport calendar\nN = 1\nobservations = []\ndef solve(first_due, interval_days, mode, completions, until):\n    due = dt.date.fromisoformat(first_due)\n    end = dt.date.fromisoformat(until) if until else None\n    step = dt.timedelta(days=interval_days)\n    for c in sorted(completions):\n        cd = dt.date.fromisoformat(c)\n        if mode == 'regenerate':\n            due = due + step\n        else:\n            due = due + step\n            while due <= cd:\n                due += step\n        if end is not None and due > end:\n            return None\n    return due.isoformat()\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: late completion on next due',\n   ['2024-01-01', 7, 'schedule', ['2024-01-08'], None],\n   '2024-01-15'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12'),\n  ('late completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-20'], None], '2024-01-27'),\n  ('out of order schedule', ['2024-01-01', 7, 'schedule', ['2024-01-20', '2024-01-02'], None], '2024-01-22'),\n  ('multiple missed schedule', ['2024-01-01', 3, 'schedule', ['2024-01-11'], None], '2024-01-13'),\n  ('until exact', ['2024-01-01', 7, 'schedule', ['2024-01-01'], '2024-01-08'], '2024-01-08'),\n  ('until passed', ['2024-01-01', 7, 'schedule', ['2024-01-01', '2024-01-08'], '2024-01-10'], None)],\n [('late completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-20'], None], '2024-01-27'),\n  ('out of order schedule', ['2024-01-01', 7, 'schedule', ['2024-01-20', '2024-01-02'], None], '2024-01-22'),\n  ('multiple missed schedule', ['2024-01-01', 3, 'schedule', ['2024-01-11'], None], '2024-01-13'),\n  ('until exact', ['2024-01-01', 7, 'schedule', ['2024-01-01'], '2024-01-08'], '2024-01-08'),\n  ('until passed', ['2024-01-01', 7, 'schedule', ['2024-01-01', '2024-01-08'], '2024-01-10'], None),\n  ('until regenerate', ['2024-02-01', 10, 'regenerate', ['2024-02-05'], '2024-02-15'], '2024-02-15'),\n  ('no completions', ['2024-02-01', 10, 'schedule', [], None], '2024-02-01'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12')],\n [('multiple missed schedule', ['2024-01-01', 3, 'schedule', ['2024-01-11'], None], '2024-01-13'),\n  ('until exact', ['2024-01-01', 7, 'schedule', ['2024-01-01'], '2024-01-08'], '2024-01-08'),\n  ('until passed', ['2024-01-01', 7, 'schedule', ['2024-01-01', '2024-01-08'], '2024-01-10'], None),\n  ('until regenerate', ['2024-02-01', 10, 'regenerate', ['2024-02-05'], '2024-02-15'], '2024-02-15'),\n  ('no completions', ['2024-02-01', 10, 'schedule', [], None], '2024-02-01'),\n  ('completion after until but due inside',\n   ['2024-03-01', 30, 'schedule', ['2024-03-05'], '2024-03-31'],\n   '2024-03-31'),\n  ('two schedule completions',\n   ['2024-04-01', 14, 'schedule', ['2024-03-30', '2024-04-10'], None],\n   '2024-04-29'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12')],\n [('until passed', ['2024-01-01', 7, 'schedule', ['2024-01-01', '2024-01-08'], '2024-01-10'], None),\n  ('until regenerate', ['2024-02-01', 10, 'regenerate', ['2024-02-05'], '2024-02-15'], '2024-02-15'),\n  ('no completions', ['2024-02-01', 10, 'schedule', [], None], '2024-02-01'),\n  ('completion after until but due inside',\n   ['2024-03-01', 30, 'schedule', ['2024-03-05'], '2024-03-31'],\n   '2024-03-31'),\n  ('two schedule completions',\n   ['2024-04-01', 14, 'schedule', ['2024-03-30', '2024-04-10'], None],\n   '2024-04-29'),\n  ('out of order regenerate',\n   ['2024-04-01', 5, 'regenerate', ['2024-04-09', '2024-04-02'], None],\n   '2024-04-14'),\n  ('regression: late completion on next due',\n   ['2024-01-01', 7, 'schedule', ['2024-01-08'], None],\n   '2024-01-15'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12')],\n [('no completions', ['2024-02-01', 10, 'schedule', [], None], '2024-02-01'),\n  ('completion after until but due inside',\n   ['2024-03-01', 30, 'schedule', ['2024-03-05'], '2024-03-31'],\n   '2024-03-31'),\n  ('two schedule completions',\n   ['2024-04-01', 14, 'schedule', ['2024-03-30', '2024-04-10'], None],\n   '2024-04-29'),\n  ('out of order regenerate',\n   ['2024-04-01', 5, 'regenerate', ['2024-04-09', '2024-04-02'], None],\n   '2024-04-14'),\n  ('regression: late completion on next due',\n   ['2024-01-01', 7, 'schedule', ['2024-01-08'], None],\n   '2024-01-15'),\n  ('early completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-05'], None], '2024-01-12'),\n  ('late completion regenerate', ['2024-01-10', 7, 'regenerate', ['2024-01-20'], None], '2024-01-27')]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Stipulated, bounded recurrence-expansion model evaluated offline on explicit fixtures; it is not a complete iCalendar implementation and makes no claim of standards conformance. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-calendar-recurrence-rules-regenerating-task-due-regenerate-base","generated_at":"2026-09-29T14:49:24.490867+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Recurring calendar series are expanded into concrete instances for display, reminders and conflict checks.","root_cause":"The regenerated due date is computed from the previous due date instead of the completion.","sha256":"481f7eecb7e258cb42b0dcb3ee79a0a6efec4b9cb5956bdb4dc5a8fe15850b46","title":"Next due date for a recurring task after completions: regenerate base · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":41.446,"exit_code":1,"observations":[{"actual":"2024-01-15","check":"regression: late completion on next due","expected":"2024-01-15","passed":true},{"actual":"2024-01-17","check":"early completion regenerate","expected":"2024-01-12","passed":false},{"actual":"2024-01-27","check":"late completion regenerate","expected":"2024-01-27","passed":true},{"actual":"2024-01-22","check":"out of order schedule","expected":"2024-01-22","passed":true},{"actual":"2024-01-13","check":"multiple missed schedule","expected":"2024-01-13","passed":true},{"actual":"2024-01-08","check":"until exact","expected":"2024-01-08","passed":true},{"actual":null,"check":"until passed","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: late completion on next due\", \"actual\": \"2024-01-15\", \"expected\": \"2024-01-15\", \"passed\": true}, {\"check\": \"early completion regenerate\", \"actual\": \"2024-01-17\", \"expected\": \"2024-01-12\", \"passed\": false}, {\"check\": \"late completion regenerate\", \"actual\": \"2024-01-27\", \"expected\": \"2024-01-27\", \"passed\": true}, {\"check\": \"out of order schedule\", \"actual\": \"2024-01-22\", \"expected\": \"2024-01-22\", \"passed\": true}, {\"check\": \"multiple missed schedule\", \"actual\": \"2024-01-13\", \"expected\": \"2024-01-13\", \"passed\": true}, {\"check\": \"until exact\", \"actual\": \"2024-01-08\", \"expected\": \"2024-01-08\", \"passed\": true}, {\"check\": \"until passed\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":40.739,"exit_code":1,"observations":[{"actual":"2024-01-15","check":"regression: late completion on next due","expected":"2024-01-15","passed":true},{"actual":"2024-01-17","check":"early completion regenerate","expected":"2024-01-12","passed":false},{"actual":"2024-01-17","check":"late completion regenerate","expected":"2024-01-27","passed":false},{"actual":"2024-01-22","check":"out of order schedule","expected":"2024-01-22","passed":true},{"actual":"2024-01-13","check":"multiple missed schedule","expected":"2024-01-13","passed":true},{"actual":"2024-01-08","check":"until exact","expected":"2024-01-08","passed":true},{"actual":null,"check":"until passed","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: late completion on next due\", \"actual\": \"2024-01-15\", \"expected\": \"2024-01-15\", \"passed\": true}, {\"check\": \"early completion regenerate\", \"actual\": \"2024-01-17\", \"expected\": \"2024-01-12\", \"passed\": false}, {\"check\": \"late completion regenerate\", \"actual\": \"2024-01-17\", \"expected\": \"2024-01-27\", \"passed\": false}, {\"check\": \"out of order schedule\", \"actual\": \"2024-01-22\", \"expected\": \"2024-01-22\", \"passed\": true}, {\"check\": \"multiple missed schedule\", \"actual\": \"2024-01-13\", \"expected\": \"2024-01-13\", \"passed\": true}, {\"check\": \"until exact\", \"actual\": \"2024-01-08\", \"expected\": \"2024-01-08\", \"passed\": true}, {\"check\": \"until passed\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}